Folding measuring instruments incorporating springs of plastic material



FOLDING MEASURING INSTRUMENTS INGORPORATING SPRINGS OF PLASTIC MATERIAL Filed 001;. 8, 1964 FIG. W

Il/ Ill/I III! ///I l// l// 4/ l/I/l ,1 1 III [HI [Hflll ILLLIIHH lllll llul M NI] IHI NH 17 18: (19:)%;)Q('21 22 2 United States Patent 3,289,302 FOLDING MEASURING INSTRUMENTS INCOR- PORATING SPRINGS 0F PLASTIC MATERIAL Andr Quenot, Besancon, Doubs, France, assignor to Etablissements Quenot & Cie S.a.r.L., Besancon, France, a firm Filed Oct. 8, 1964, Ser. No. 402,536 Claims priority, application France, June 9, 1964,

2 Claims. (cl. 33-105 This application discloses an improvement over the folding rule disclosed and claimed in assignees co-pending application, Ser. No. 369,664, filed May 25, 1964.

The specification of said co-pending application has for its object a folding measuring instrument constituted by rigid elements pivotally secured endwise and carrying scales extending from the free end of the first element up to the free end of the last element, a spring being provided on the pivotal connection between any two successive elements, each spring including a male and a female section, which sections are rigid respectively with the cooperating pivotally interconnected ends of said elements while at least one of said spring elements is made of plastic material bestowed with lubricating and mechanical resisting properties cooperating with those of the other sections; the measuring elements were pivotally interconnected two by two by means of a rivet made of brass. It has appeared necessary hitherto toresort to a metal rivet for the connection between the pivotal elements since the mechanical stresses which define the resistance of the pivotal connections against tearing out may reach substantial values which it was not possible until recent times to obtain through the use of plastic material.

Now, recent developments in the field of plastic material have however brought to light properties inherent to certain synthetic resins, chiefly the acetate resin or the acetal resin sold under the registered trade name Delrin. Said material allows for instance deformation at room temperature and has a resistance against tearing off which reliably guarantees the proper operation of arrangements assembled by means of rivets made therewith.

The present invention has therefore for its object a folding measuring instrument including a number of rigid elements pivotally connected together endwise and carrying scales extending according to an arithmetic progression from the free end of the first element up to the free end of the last element, a spring being inserted at the pivotal connection between any two successive elements and including as mentioned *a male section and a female section rigid respectively with each of the cooperating pivotally interconnected ends of the successive elements, at least one of said spring sections being made of plastic material having lubricating and mechanical resistant properties matching those of the other sections; according to the invention, the pivotal connection between the elements is constituted by a rivet of plastic material.

According to a further feature of the invention, one of the sections of the spring fitted between the two elements is formed integrally with the rivet and revolves in unison with one of the elements through the agency of flanges folded over the sides of the latter.

The accompanying drawings illustrate, by way of example, in a non-limiting sense, a preferred embodiment of the invention, together with a modification thereof. In said drawings:

FIG. 1 is a partial sectional view of a first embodiment of the invention.

FIG. 2 illustrates a modification of the embodiment illustrated in FIG. 1.

FIG. 3 is a plan view of the modification illustrated in FIG. 2.

I The elements 1 and 2 forming part of the measuring instrument are'made ofmetal and preferably of the alloy sold under the registered tradename Duralumin; the male section of the spring is stamped within the actual'material forming the element 2 so as to form bosses 3. The female section of the spring is constituted by a. plate 4 formed integrally with the rivet 5 of which the head projects beyond the elements as illustrated in FIG. 1. Said plate 4 is provided with recesses 6 adapted to cooperate with the bosses 3 as soon as the elements 1 and 2 are in a predetermined position with reference to each other, generally in an aligned position.

In FIG. 2, the assembly is similar, except for the fact that the rivet heads 5 are embedded Within the corresponding elements 1 and 2.

As illustrated in FIG. 3, the plate 4 is rigidly secured to the element 1 so as to rotate in unison therewith as provided by its depending flanges 7 folded over the edges of the element 1.

Obviously, the section 4 of the spring may be secured to the element 1 through other means, for instance through the agency of a stud interconnecting said two parts.

Obviously also, the bosses forming part of the spring may be obtained by a shaping of the plate 4 which is then caused to rotate in unison with one of the elements, while the recesses are then formed in the other element.

The plastic material forming one of the sections of the spring and the assembling rivet between the elements is advantageously constituted by an acetate resin or by that sold under the registered trade name Delrin. Tests have shown that such a material is particularly adapted to be crushed at room temperature, so as to form rivet heads, while its resistance against tearing off satisfies the requirements of folding measuring instruments.

Such arrangements may also be executed more simply since a single part operates both as a section of a spring and as a part of the assembling rivet. Simultaneously, the frictional problems are solved advantageously, since the movable parts engaging each other are constituted, on the one hand, by plastic material and, on the other hand, by metal, whereby the relative friction between the parts leads to a minimum wear.

In the case of arrangements of which the elements are made of wood, one of the sections of the spring can again be made of plastic material formed in one with the corresponding rivet and adapted to move in unison with one of the elements of the arrangement, while the other section of the spring may be made of metal and be adapted to move in unison with the other element.

What I claim is:

1. A folding measuring rule, comprising, in combination:

(A) a plurality of adjacent elements interconnected over a cooperating area and carrying successive sections of a scale, said elements being pivotally secured together by a rivet; including heads countersunk in the outer surfaces of said elements;

(B) one of said elements having bosses formed therein on either side of said rivet, the end of another of said elements cooperating with said one element being recessed along its longitudinal edges;

(C) a spring element formed integrally with said rivet and fitted between said elements, said spring element and rivet consisting of a resilient self-lubricating plastic material secured to the recessed. end of another element by having portions thereof folded thereover, said spring element having recesses adapted to receive said bosses of said one element therein for holding said adjacent elements in alignment or in superimposition.

2. The combination according to claim 1 wherein said spring element is composed of nylon.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Keulfel 33-105 Prout 33--105 Gasstran et a1. 33120 McCaffrey 33--120 Stowell "33-119 X Green.

Kahn et a1. 267 -1 X 4 FOREIGN PATENTS 2/1964 Switzerland.

OTHER REFERENCES LEONARD FORMAN, Primary Examiner. H. N. HARIOAN, Assistant Examiner. 

1. A FOLDING MEASURING RULE, COMPRISING, IN COMBINATION: (A) A PLURALITY OF ADJACENT ELEMENTS INTERCONNECTED OVER A COOPERATING AREA AND CARRYING SUCCESSIVE SECTIONS OF A SCALE, SAID ELEMENTS BEING PIVOTALLY SECURED TOGETHER BY A RIVET; INCLUDING HEADS COUNTERSUNK IN THE OUTER SURFACES OF SAID ELEMENTS; (B) ONE OF SAID ELEMENTS HAVING FORMED THEREIN ON EITHER SIDE OF SAID RIVET, THE END OF ANOTHER OF SAID ELEMENTS COOPERATING WITH SAID ONE ELEMENT BEING RECESSED ALONG ITS LONGITUDINAL EDGES; (C) A SPRING ELEMENT FORMED INTEGRALLY WITH SAID RIVET AND FITTED BETWEEN SAID ELEMENTS, SAID SPRING ELEMENT AND RIVET CONSISTING OF A RESILIENT SELF-LUBRICATING PLASTIC MATERIAL SECURED TO THE RECESSED END OF ANOTHER ELEMENT BY HAVING PORTIONS THEREOF FOLDED THEREOVER SAID SPRING ELEMENT HAVING RECESSES ADAPTED TO RECEIVE SAID BOSSES OF SAID ONE ELEMENT THEREIN FOR HOLDING SAID ADJACENT ELEMENTS IN ALIGNMENT OR IN SUPERIMPOSITION. 